ETL vs ELT Explained Simply (With a SQL Transform Example)
What ETL and ELT mean, how they differ, what the transform step looks like in real SQL, full vs incremental loads, and which approach to choose for your data warehouse.
Star Schema vs Snowflake Schema: Fact and Dimension Tables Explained
What a star schema is, how fact and dimension tables work, how to query them with plain SQL, how the snowflake schema differs, and which one to choose for your data warehouse.
OLTP vs OLAP Explained Simply (With SQL Examples)
What OLTP and OLAP mean, how they differ, why heavy reports slow down a live database, and how data moves from one to the other, explained in plain English with SQL examples.
5 Best Big Data and Data Engineering Books for SQL Users
The best books on big data, data warehousing and data engineering for people who already know SQL, from Fundamentals of Data Engineering to Learning Spark.
25 SQL Interview Questions for Beginners (With Answers)
25 SQL interview questions that come up again and again for junior roles, with short answers you can say out loud: joins, GROUP BY, NULL, keys, indexes, ACID, and three classic write-a-query tasks.
5 Best SQL Performance Tuning Books (Including 2 Free Ones)
The best books for SQL performance tuning: indexes, execution plans and troubleshooting slow SQL Server queries. Two of them are free ebooks.
What Is Delphi? Install Delphi Community Edition and Build Your First App
A beginner’s guide to Delphi: what it is, what it’s used for, how to install the free Community Edition, and how to build your first Windows app step by step.
Top N per Group in SQL Server: Get the Latest Record for Each Group
How to get the latest record or the top N rows for each group in SQL Server with ROW_NUMBER(), handle ties correctly, and when CROSS APPLY or WITH TIES is the better choice.
T-SQL Fundamentals (4th Edition) Review: Is It the Best SQL Server Book?
An honest review of Itzik Ben-Gan’s T-SQL Fundamentals, 4th edition: what it covers, who it is for, its strengths and weaknesses, and whether you should buy it.
SQL DISTINCT and Column Aliases Explained Simply
How SQL DISTINCT removes duplicate rows (and why it applies to every selected column), how it treats NULL, COUNT(DISTINCT), and how to use column and table aliases, including why an alias works in ORDER BY but not in WHERE.